Study On Emission Characteristics Of Fine Particulate Matters From In-use Diesel Vehicles And Analysis Of Mitigating Potential In The Guanzhong Region, China

Regional haze result from PM2.5 has frequently appeared in recent year, and vehicle exhaust emissions are one of the main sources. More than 90% of the vehicular PM2.5 are emitted from diesel vehicles. Further research on emission characteristics and emissions inventories of PM2.5 from diesel vehicles exhaust is needed to develop effective emission mitigating strategies and to improve urban air quality. This thesis studied the size concentration distributions of number and mass of particles, the chemical composition and the emissions inventory of PM2.5 from in-use diesel vehicles exhaust. The emission mitigating potential by installing after-treatment devices on diesel vehicles in Guanzhong region were also researched, which is of importance to reduce haze pollution in this region. The main results were given as follows:(1)This paper uses dynamometer test methods to investigate the size distributions of particle number concentration and mass concentration of exhaust particulates from a light duty diesel vehicle(LDDV) and two heavy duty diesel vehicles(HDDV), with an electrical low-pressure impactor(ELPI). There are some significant differences between number concentration and mass concentration of PM2.5 emitted from HDDV. The PM0.1 number consistence which diameter smaller than 108 nm account for 73.09% of the all, but the PM mass consistence which diameter bigger than 108 nm account for 96.4% of the all. For number concentration and mass concentration of PM2.5 emitted from LDDV, Accumulation Mode Particles in the range of 108nm~1μm dominate, accounting for 85.31% and 56.25% of number concentration and mass concentration, respectively.(2)PM2.5 from diesel vehicle exhaust was collected and inorganic ions, inorganic element, OC(organic carbon) and EC(inorganic carbon) of the PM2.5 were studied using IC, ICP-AES and TOT. The results showed that for HDDV and LDDV, the chemical composition of PM2.5 from exhaust is similar. The unknown compositions of PM2.5 from HDDV and LDDV were 33.62% and 27.59%, respectively. OC was the lagest component in PM2.5 from HDDV and LDDV, accounting for 39.00% and 49.72%, respectively. EC is corresponding accounting for 22.72% and 19.84%. While inorganic ions made up less than 4% and inorganic element was below 1%. The main component of carbonaceous species was OC. NO3-、SO42-and Na+ were the richest inorganic ions and Al、Ca、Fe and Mg were the highest amount of inorganic elementsThis paper established an inventory of diesel vehicle emissions of the Guanzhong region. In Guanzhong region, the ownership of diesel vehicles reach 0.38 million in 2012, accounting for 11.61% of total vehicles. NOx and PM2.5 emissions from diesel vehicles were 10×104 tons and 0.32×104 tons, accounting for 76.39% and 78.05% of total vehicles respectively. Large passenger car and heave duty truck are the main sources of NOx and PM2.5, accounting for more than 70% of total diesel vehicles. In order to reduce pollutant emission from diesel vehicles exhaust, about 3.99×104 diesel vehicles(large passenger car and heave duty truck) which were compliant to the China emission standard stage III were installed diesel particulate filter(DPF). It would cost 1.597 billion yuan. After doing that, it could reduce PM2.5 emissions 490.73 tons one year.